PBCH Transmission Method and Apparatus

ABSTRACT

A physical broadcast channel (PBCH) transmission method and an apparatus. The method includes scrambling PBCH based on a first scrambling code of the PBCH, where the first scrambling code is one of four scrambling codes, where a combination of a second least significant bit and a third least significant bit of a system frame number (SFN) indicates one value of four values, and where the four scrambling codes have a one-to-one correspondence with the four values, and sending the PBCH to a terminal device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage of International Application No.PCT/CN2018/085589, filed on May 4, 2018, which claims priority toChinese Patent Application No. 201710309546.9, filed on May 4, 2017.Both of the aforementioned applications are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

This application relates to communications technologies, and inparticular, to a physical broadcast channel (PBCH) transmission methodand an apparatus.

BACKGROUND

In a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)system, a network side uses a PBCH to send a cell broadcast message: amaster information block (MIB). The MIB has a total of 24 bits,including three bits for a system bandwidth, indicating one of sixbandwidths: 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz, one bitfor physical hybrid automatic repeat request indicator channel duration(PHICH-duration), indicating normal or extended (Extend) PHICH-duration,two bits for a PHICH-resource (source), corresponding to a PHICHparameter Ng={1/6,1/2,1,2}, eight bits for a system frame number (SFN),where the eight bits are eight most significant bits of the SFN, and 10reserved bits. After a cell search procedure, a terminal device achievessubframe synchronization and frame synchronization by using asynchronization signal, that is, learns of a location of a subframe 0 ina radio frame. A PBCH is on first four orthogonal frequency divisionmultiplexing (OFDM) symbols in a second timeslot (slot) in a subframe 0in time domain, and occupies 72 central subcarriers in frequency domain.The PBCH is sent repeatedly for four times within a 40-ms transmissiontime interval (TTI), that is, one PBCH is sent every 10 ms. The sentPBCHs carry same and self-decodable coded bits. Therefore, when asignal-to-interference ratio (SIR) is high enough, the terminal devicecan successfully decode PBCH content by receiving only one of the PBCHssent within 40 ms. If decoding fails, the terminal device performsdecoding by softly combining a current PBCH and a PBCH sent at a next 10ms, until the terminal device successfully decodes the PBCH. In LTE, anSFN has a length of 10 bits. In a MIB broadcast by a PBCH, first eightbits of an SFN are broadcast, and the two remaining bits are determinedbased on a location, in a 40-ms period window, of a frame in which thePBCH is sent. Two least significant bits of an SFN on a PBCH in a first10-ms frame within the 40 ms are 00, two least significant bits of anSFN on a PBCH in a second 10-ms frame within the 40 ms are 01, two leastsignificant bits of an SFN on a PBCH in a third 10-ms frame within the40 ms are 00, and two least significant bits of an SFN on a PBCH in afourth 10-ms frame within the 40 ms are 11. Within each 40 ms when abase station sends PBCHs, the base station uses four different phases ofa PBCH scrambling code to represent different occasions. Differentphases are corresponding to different 10-ms frames. In other words, twoleast significant bits of an SFN corresponding to one phase aredifferent from two least significant bits of an SFN corresponding toanother phase. In addition, the scrambling code is reset every 40 ms.After receiving the PBCH, the terminal device attempts to decode thePBCH using each of the four phases. If decoding succeeds, the terminaldevice knows in which 10-ms frame within 40 ms the base station sendsthe PBCH, determines the two least significant bits of the SFN based ona mapping relationship between the four different phases of thescrambling code and the two least significant bits of SFNs, and finallydetermines all the 10 bits of the SFN.

In a fifth generation (5G) system, a higher spectrum band is used than aspectrum band used in LTE. Therefore, radio signal transmissionattenuation increases, and radio signal coverage reduces. In this case,a beamforming technology of massive multiple-input multiple-output(massive MIMO) is used by using a plurality of antennas of a basestation to obtain high antenna gains, so as to complement path losses.Multi-beam transmission is supported for synchronization signals andPBCHs in 5G, to facilitate reception of terminal devices in a cell.Multi-beam transmission of synchronization signals (SS) is implementedby defining an SS burst set. One SS burst set includes one or more SSbursts, and one SS burst includes one or more SS blocks. One SS block isused to carry a synchronization signal of one beam. Therefore, one SSburst set includes synchronization signals of beams that are of a samequantity as SS blocks in the cell. One SS block includes one symbol fora primary synchronization signal (PSS), one symbol for a secondarysynchronization signal (SSS), and two symbols for PBCHs. The SSS may beused as a demodulation reference signal for the PBCH. An SS burst setsending periodicity includes a default 20-ms periodicity andnetwork-indicated periodicities. The network-indicated periodicitiesinclude 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, and 160 ms. In 5G, a PBCH issent in an SS block, and a PBCH TTI is 80 ms. Therefore, within 80 ms,the base station may send 4 PBCHs at the default 20-ms SS block sendingperiodicity, or may send 16 PBCHs at an indicated 5-ms SS block sendingperiodicity, or may send eight PBCHs at an indicated 10-ms SS blocksending periodicity, . . . .

In a 5G system, because a PBCH is sent in an SS block while there are aplurality of SS block sending periodicities, including the defaultperiodicity and the network-indicated periodicities, the PBCH is nolonger sent at a fixed interval of 10 ms as in LTE. Therefore, in 5G, asolution is needed how to use a PBCH to indicate an SFN of a radio framein which the PBCH is located.

SUMMARY OF THE INVENTION

This application provides a PBCH transmission method and an apparatus,so as to use a PBCH to indicate an SFN of a radio frame in which thePBCH is located.

According to a first aspect, this application provides a PBCHtransmission method, including receiving, by a terminal device, a PBCHsent by a network device, where the PBCH includes seven most significantbits of an SFN of a radio frame in which the PBCH is located,determining, by the terminal device, a least significant bit of the SFNbased on indication information of the least significant bit of the SFN,determining, by the terminal device based on the PBCH, at least one of ascrambling code, a cyclic redundancy check (CRC) check mask, or aredundancy version of the PBCH, and determining two remaining bits ofthe SFN based on a one-to-one correspondence between the two remainingbits of the SFN and the at least one of the scrambling code, the CRCcheck mask, or the redundancy version of the PBCH, where the tworemaining bits are a second least significant bit and a third leastsignificant bit of the SFN, and determining, by the terminal devicebased on the least significant bit, the seven most significant bits, thesecond least significant bit, and the third least significant bit of theSFN, the SFN of the radio frame in which the PBCH is located. Thisimplements that the terminal device can determine the two remaining bitsof the SFN by just performing blind detection on at least one of thefollowing: four scrambling codes, four CRC check masks, or fourredundancy versions. In comparison with an implementation of directlysetting eight scrambling codes to determine an SFN of a frame in which aPBCH is located, a quantity of blind detections is reduced from 8 to 4,thereby reducing blind detection complexity. In addition, the foregoingimplementation can be applicable to scenarios with different quantitiesof PBCHs sent within one PBCH TTI. To be specific, the foregoingimplementation can be applicable to scenarios in which one PBCH, twoPBCHs, four PBCHs, eight PBCHs, or 16 PBCHs can be sent within one TTI.An application scope is relatively wide.

In a possible design of the first aspect, the indication information ofthe least significant bit of the SFN is indicated by one bit at a presetlocation on the PBCH.

In a possible design of the first aspect, the indication information ofthe least significant bit of the SFN is indicated by a relative locationrelationship between a primary synchronization signal and a secondarysynchronization signal in a synchronization signal block in which thePBCH is located.

In a possible design of the first aspect, a scrambling codecorresponding to two remaining bits of one SFN and a scrambling codecorresponding to two remaining bits of another SFN are differentsegments of one scrambling code sequence, where the two remaining bitsof the one SFN are different from the two remaining bits of the anotherSFN, or a scrambling code corresponding to two remaining bits of one SFNand a scrambling code corresponding to two remaining bits of another SFNare different scrambling code sequences, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

In a possible design of the first aspect, a CRC check mask correspondingto two remaining bits of one SFN and a CRC check mask corresponding totwo remaining bits of another SFN are different mask sequences, wherethe two remaining bits of the one SFN are different from the tworemaining bits of the another SFN.

In a possible design of the first aspect, a redundancy versioncorresponding to two remaining bits of one SFN and a redundancy versioncorresponding to two remaining bits of another SFN are differentredundancy versions obtained by performing different rate matching onencoded information carried on the PBCH, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

According to a second aspect, this application provides a PBCHtransmission method, including determining, by a network device, an SFNof a radio frame in which a PBCH is located, adding seven mostsignificant bits of the SFN to the PBCH, and determining indicationinformation of a least significant bit of the SFN, determining, by thenetwork device, at least one of a scrambling code, a CRC check mask, ora redundancy version of the PBCH, where the at least one of thescrambling code, the CRC check mask, or the redundancy version is thesame within one radio frame group, and is different in different radioframe groups, and the radio frame group are two radio frames for whichSFN mod 8=2n and SFN mod 8=2n+1 among eight consecutive radio frames inwhich a radio frame for which SFN mod 8=0 is used as a start frame,where n=0, 1, 2, 3, within one radio frame group, two remaining bits ofan SFN of one radio frame are the same as two remaining bits of an SFNof the other radio frame, and the two remaining bits are a second leastsignificant bit and a third least significant bit of the SFN, andprocessing, by the network device, the PBCH based on the at least one ofthe scrambling code, the CRC check mask, or the redundancy version ofthe PBCH, and sending the PBCH to a terminal device in the radio framecorresponding to the SFN.

In a possible design of the second aspect, the indication information ofthe least significant bit of the SFN is indicated by one bit at a presetlocation on the PBCH.

In a possible design of the second aspect, the indication information ofthe least significant bit of the SFN is indicated by a relative locationrelationship between a primary synchronization signal and a secondarysynchronization signal in a synchronization signal block in which thePBCH is located.

In a possible design of the second aspect, a scrambling codecorresponding to two remaining bits of one SFN and a scrambling codecorresponding to two remaining bits of another SFN are differentsegments of one scrambling code sequence, where the two remaining bitsof the one SFN are different from the two remaining bits of the anotherSFN, or a scrambling code corresponding to two remaining bits of one SFNand a scrambling code corresponding to two remaining bits of another SFNare different scrambling code sequences, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

In a possible design of the second aspect, a CRC check maskcorresponding to two remaining bits of one SFN and a CRC check maskcorresponding to two remaining bits of another SFN are different masksequences, where the two remaining bits of the one SFN are differentfrom the two remaining bits of the another SFN.

In a possible design of the second aspect, a redundancy versioncorresponding to two remaining bits of one SFN and a redundancy versioncorresponding to two remaining bits of another SFN are differentredundancy versions obtained by performing different rate matching onencoded information carried on the PBCH, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

According to a third aspect, this application provides a terminaldevice, including a receiving module, configured to receive a PBCH sentby a network device, where the PBCH includes seven most significant bitsof an SFN of a radio frame in which the PBCH is located, and adetermining module, configured to determine a least significant bit ofthe SFN based on indication information of the least significant bit ofthe SFN. The determining module is further configured to determine,based on the PBCH, at least one of a scrambling code, a CRC check mask,or a redundancy version of the PBCH, and determine two remaining bits ofthe SFN based on a one-to-one correspondence between the two remainingbits of the SFN and the at least one of the scrambling code, the CRCcheck mask, or the redundancy version of the PBCH. The two remainingbits are a second least significant bit and a third least significantbit of the SFN. The determining module is further configured todetermine, based on the least significant bit, the seven mostsignificant bits, the second least significant bit, and the third leastsignificant bit of the SFN, the SFN of the radio frame in which the PBCHis located.

In a possible design of the third aspect, the indication information ofthe least significant bit of the SFN is indicated by one bit at a presetlocation on the PBCH.

In a possible design of the third aspect, the indication information ofthe least significant bit of the SFN is indicated by a relative locationrelationship between a primary synchronization signal and a secondarysynchronization signal in a synchronization signal block in which thePBCH is located.

In a possible design of the third aspect, a scrambling codecorresponding to two remaining bits of one SFN and a scrambling codecorresponding to two remaining bits of another SFN are differentsegments of one scrambling code sequence, where the two remaining bitsof the one SFN are different from the two remaining bits of the anotherSFN, or a scrambling code corresponding to two remaining bits of one SFNand a scrambling code corresponding to two remaining bits of another SFNare different scrambling code sequences, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

In a possible design of the third aspect, a CRC check mask correspondingto two remaining bits of one SFN and a CRC check mask corresponding totwo remaining bits of another SFN are different mask sequences, wherethe two remaining bits of the one SFN are different from the tworemaining bits of the another SFN.

In a possible design of the third aspect, a redundancy versioncorresponding to two remaining bits of one SFN and a redundancy versioncorresponding to two remaining bits of another SFN are differentredundancy versions obtained by performing different rate matching onencoded information carried on the PBCH, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

According to a fourth aspect, this application provides a networkdevice, including a determining module, configured to determine an SFNof a radio frame in which a PBCH is located, add seven most significantbits of the SFN to the PBCH, and determine indication information of aleast significant bit of the SFN, where the determining module isfurther configured to determine at least one of a scrambling code, a CRCcheck mask, or a redundancy version of the PBCH, where the at least oneof the scrambling code, the CRC check mask, or the redundancy version isthe same within one radio frame group, and is different in differentradio frame groups, and the radio frame group are two radio frames forwhich SFN mod 8=2n and SFN mod 8=2n+1 among eight consecutive radioframes in which a radio frame for which SFN mod 8=0 is used as a startframe, where n=0, 1, 2, 3, within one radio frame group, two remainingbits of an SFN of one radio frame are the same as two remaining bits ofan SFN of the other radio frame, and the two remaining bits are a secondleast significant bit and a third least significant bit of the SFN, anda sending module, configured to process the PBCH based on the at leastone of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH, and send the PBCH to a terminal device in the radioframe corresponding to the SFN.

In a possible design of the fourth aspect, the indication information ofthe least significant bit of the SFN is indicated by one bit at a presetlocation on the PBCH.

In a possible design of the fourth aspect, the indication information ofthe least significant bit of the SFN is indicated by a relative locationrelationship between a primary synchronization signal and a secondarysynchronization signal in a synchronization signal block in which thePBCH is located.

In a possible design of the fourth aspect, a scrambling codecorresponding to two remaining bits of one SFN and a scrambling codecorresponding to two remaining bits of another SFN are differentsegments of one scrambling code sequence, where the two remaining bitsof the one SFN are different from the two remaining bits of the anotherSFN, or a scrambling code corresponding to two remaining bits of one SFNand a scrambling code corresponding to two remaining bits of another SFNare different scrambling code sequences, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

In a possible design of the fourth aspect, a CRC check maskcorresponding to two remaining bits of one SFN and a CRC check maskcorresponding to two remaining bits of another SFN are different masksequences, where the two remaining bits of the one SFN are differentfrom the two remaining bits of the another SFN.

In a possible design of the fourth aspect, a redundancy versioncorresponding to two remaining bits of one SFN and a redundancy versioncorresponding to two remaining bits of another SFN are differentredundancy versions obtained by performing different rate matching onencoded information carried on the PBCH, where the two remaining bits ofthe one SFN are different from the two remaining bits of the anotherSFN.

According to a fifth aspect, this application provides a communicationssystem, including any terminal device provided in the third aspect andany network device provided in the fourth aspect.

According to a sixth aspect, this application provides a terminaldevice, including a transceiver, a memory, configured to store aninstruction, and a processor, connected to both the memory and thetransceiver, and configured to execute the instruction, so as to performthe following steps when executing the instruction receiving a PBCH sentby a network device, where the PBCH includes seven most significant bitsof an SFN of a radio frame in which the PBCH is located, determining aleast significant bit of the SFN based on indication information of theleast significant bit of the SFN, determining, based on the PBCH, atleast one of a scrambling code, a CRC check mask, or a redundancyversion of the PBCH, and determining two remaining bits of the SFN basedon a one-to-one correspondence between the two remaining bits of the SFNand the at least one of the scrambling code, the CRC check mask, or theredundancy version of the PBCH, where the two remaining bits are asecond least significant bit and a third least significant bit of theSFN, and determining, based on the least significant bit, the seven mostsignificant bits, the second least significant bit, and the third leastsignificant bit of the SFN, the SFN of the radio frame in which the PBCHis located.

According to a seventh aspect, this application provides a networkdevice, including a transceiver, a memory, configured to store aninstruction, and a processor, connected to both the memory and thetransceiver, and configured to execute the instruction, so as to executethe following steps when executing the instruction determining an SFN ofa radio frame in which a PBCH is located, adding seven most significantbits of the SFN to the PBCH, determining indication information of aleast significant bit of the SFN, determining at least one of ascrambling code, a CRC check mask, or a redundancy version of the PBCH,where the at least one of the scrambling code, the CRC check mask, orthe redundancy version is the same within one radio frame group, and isdifferent in different radio frame groups, and the radio frame group aretwo radio frames for which SFN mod 8=2n and SFN mod 8=2n+1 among eightconsecutive radio frames in which a radio frame for which SFN mod 8=0 isused as a start frame, where n=0, 1, 2, 3, within one radio frame group,two remaining bits of an SFN of one radio frame are the same as tworemaining bits of an SFN of the other radio frame, and the two remainingbits are a second least significant bit and a third least significantbit of the SFN, and processing the PBCH based on the at least one of thescrambling code, the CRC check mask, or the redundancy version of thePBCH, and sending the PBCH to a terminal device in the radio framecorresponding to the SFN.

According to an eighth aspect, this application further provides areadable storage medium that contains an executable instruction. When atleast one processor of a terminal device executes the executableinstruction, the terminal device is configured to execute the method inthe first aspect or any one of the possible implementations of the firstaspect.

According to a ninth aspect, this application further provides areadable storage medium that contains an executable instruction. When atleast one processor of a network device executes the executableinstruction, the network device is configured to execute the method inthe second aspect or any one of the possible implementations of thesecond aspect.

According to a tenth aspect, this application further provides a programproduct. The program product includes an executable instruction, and theexecutable instruction is stored in a computer readable storage medium.At least one processor of a terminal device may read the computerexecutable instruction from the readable storage medium, and the atleast one processor executes the executable instruction, so that theterminal device implements the method in the first aspect or any one ofthe possible implementations of the first aspect.

According to an eleventh aspect, this application further provides aprogram product. The program product includes an executable instruction,and the executable instruction is stored in a computer readable storagemedium. At least one processor of a network device may read the computerexecutable instruction from the readable storage medium, and the atleast one processor executes the executable instruction, so that thenetwork device implements the method in the second aspect or any one ofthe possible implementations of the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a PBCH sending location in an LTEsystem;

FIG. 2 is a schematic diagram of an application scenario according tothis application;

FIG. 3 is a signaling interaction diagram of a PBCH transmission methodaccording to this application;

FIG. 4A is a schematic diagram of an implementation of indicationinformation of a least significant bit of an SFN according to anembodiment shown in FIG. 3;

FIG. 4B is a schematic diagram of another implementation of indicationinformation of a least significant bit of an SFN according to anembodiment shown in FIG. 3;

FIG. 5A is a schematic diagram of locations of PBCHs sent within an80-ms TTI at a sending interval of 20 ms according to an embodimentshown in FIG. 3;

FIG. 5B is a schematic diagram of locations of PBCHs sent within an80-ms TTI at a sending interval of 10 ms according to an embodimentshown in FIG. 3;

FIG. 5C is a schematic diagram of locations of PBCHs sent within an80-ms TTI at a sending interval of 5 ms according to an embodiment shownin FIG. 3;

FIG. 6 is a schematic structural diagram of Embodiment 1 of a terminaldevice according to this application;

FIG. 7 is a schematic structural diagram of Embodiment 2 of a terminaldevice according to this application;

FIG. 8 is a schematic structural diagram of Embodiment 1 of a networkdevice according to this application; and

FIG. 9 is a schematic structural diagram of Embodiment 2 of a networkdevice according to this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A PBCH transmission method provided in this application is applied to a5G system. A network device sends a PBCH to a terminal device, so as tosend a MIB of a cell through the PBCH. After receiving the PBCH, theterminal device determines, based on the MIB carried on the PBCH, eightmost significant bits of an SFN of a radio frame in which the PBCH islocated. FIG. 1 is a schematic diagram of a PBCH sending location in anLTE system. In the LTE system, the PBCH sending location is shown inFIG. 1. A master information block includes 14 information bits, 10reserved bits, and a 16-bit cyclic redundancy check (CRC) code. Encodingis performed to obtain 120 bits of encoded data, and then rate matchingis performed to output 1920 bits. This is equivalent to 16 repetitionsof the 120 bits of encoded data. Then, the 1920 bits of data isscrambled to obtain 1920 bits of scrambled data, with a scramblinglength of 1920 bits. The 1920 bits of scrambled data is evenly dividedinto four segments, with 480 bits in each segment. Therefore, a finalquantity of bits carried on a PBCH sent in a radio frame is 480 bits.Within a 40-ms TTI of the PBCH, the PBCH is sent every 10 ms. The PBCHis on first four OFDM symbols in a second timeslot in a subframe 0 intime domain, and occupies 72 subcarriers in frequency domain. For thesent PBCHs, scrambling codes of the PBCHs are different, and there is amapping relationship between the scrambling code and two leastsignificant bits of the SFN. Therefore, after receiving the PBCH, theterminal device may determine the scrambling code of the PBCH whiledecoding the PBCH, and finally determine the two least significant bitsof the SFN. Finally, the terminal device determines 10 bits of the SFNof the radio frame in which the PBCH is located. However, in 5G, a PBCHis sent in an SS block, while there are a plurality of SS block sendingperiodicities. In addition, in 5G, a PBCH TTI is 80 ms. Within one TTI,a quantity of PBCHs sent by the network device is indefinite. Therefore,an LTE manner of indicating an SFN of a radio frame in which a PBCH islocated can no longer be used. This application intends to implementindication of an SFN of a radio frame in which a PBCH is located in a 5Gsystem.

FIG. 2 is a schematic diagram of an application scenario according tothis application. As shown in FIG. 2, this application is applied to asystem using a beamforming technology. A cell includes a total of eightbeams B0 to B7 sent by a network device 23. The beam B2 can cover aterminal device 21, and a terminal device 22 cannot be covered by thebeam B2. Multi-beam transmission is supported for synchronizationsignals and PBCHs in the system, to facilitate reception of terminaldevices in the cell. According to a PBCH transmission method provided inthis application, a network device determines an SFN of a radio frame inwhich a PBCH is located, adds seven most significant bits of the SFN tothe PBCH, and determines indication information of a least significantbit of the SFN. The network device determines at least one of ascrambling code, a CRC check mask, or a redundancy version of the PBCH.The at least one of the scrambling code, the CRC check mask, or theredundancy version is the same within one radio frame group, and isdifferent in different radio frame groups. The radio frame group are tworadio frames for which SFN mod 8=2n and SFN mod 8=2n+1 among eightconsecutive radio frames in which a radio frame for which SFN mod 8=0 isused as a start frame, where n=0, 1, 2, 3. Within one radio frame group,two remaining bits of an SFN of one radio frame are the same as tworemaining bits of an SFN of the other radio frame. The two remainingbits are a second least significant bit and a third least significantbit of the SFN. The network device processes the PBCH based on the atleast one of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH, and sends the PBCH to a terminal device in theradio frame corresponding to the SFN. The terminal device receives thePBCH sent by the network device. The PBCH includes the seven mostsignificant bits of the SFN of the radio frame in which the PBCH islocated. The terminal device determines the least significant bit of thePBCH based on the indication information of the least significant bit ofthe SFN. The terminal device determines, based on the PBCH, the at leastone of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH, and determines the two remaining bits of the SFNbased on a one-to-one correspondence between the two remaining bits ofthe SFN and the at least one of the scrambling code, the CRC check mask,or the redundancy version of the PBCH. The terminal device determines,based on the least significant bit, the seven most significant bits, thesecond least significant bit, and the third least significant bit, theSFN of the radio frame in which the PBCH is located. This implementsthat, in a 5G system, the terminal device can determine the tworemaining bits of the SFN by just performing blind detection on at leastone of the following: four scrambling codes, four CRC check masks, orfour redundancy versions. In comparison with an implementation ofdirectly setting eight scrambling codes to determine an SFN of a radioframe in which a PBCH is located, a quantity of blind detections isreduced from 8 to 4, thereby reducing blind detection complexity. Inaddition, the PBCH transmission method can be applicable to scenarioswith different quantities of PBCHs sent within one PBCH TTI. To bespecific, the foregoing implementation can be applicable to scenarios inwhich one PBCH, two PBCHs, four PBCHs, eight PBCHs, or 16 PBCHs can besent within one TTI. An application scope is relatively wide.

The following details a receive end signal obtaining method provided inthis application with reference to the accompanying drawing.

FIG. 3 is a signaling interaction diagram of a PBCH transmission methodaccording to this application. As shown in FIG. 3, the PBCH transmissionmethod provided in this application includes the following steps.

S301: A network device determines an SFN of a radio frame in which aPBCH is located, adds seven most significant bits of the SFN to thePBCH, and determines indication information of a least significant bitof the SFN.

Specifically, the network device in this application may be a basestation (BTS) in Global System for Mobile Communications (GSM) or CodeDivision Multiple Access (CDMA), or may be a NodeB (NB) in Wideband CodeDivision Multiple Access (WCDMA), or may be an evolved NodeB (eNB oreNodeB), a relay node, or an access point in LTE, or a new radio accesstechnology (NR) base station in a 5G network, or the like. This is notlimited herein.

When determining to send a PBCH to the terminal device, the networkdevice first determines a radio frame in which the PBCH is sent, thatis, an SFN of the radio frame in which the PBCH is located. An SFNincludes 10 bits. In this application, it is defined that bits of an SFNare numbered from left to right as a first bit, a second bit, a thirdbit, . . . , a ninth bit, and a tenth bit, respectively. The first bitto the seventh bit of the SFN are referred to as seven most significantbits of the SFN, the tenth bit is referred to as a least significant bitof the SFN, the ninth bit is referred to as a second least significantbit of the SFN, and the eighth bit is referred to as a third leastsignificant bit of the SFN.

In this application, the network device adds the seven most significantbits of the SFN to the PBCH. This means that the network devicenotifies, in an explicit way, the terminal device of the seven mostsignificant bits of the SFN of the radio frame in which the PBCH islocated. The least significant bit of the SFN may be indicated by theindication information of the least significant bit, and the indicationinformation may be an indication in an explicit way or an implicit way.

In a possible implementation, the indication information of the leastsignificant bit of the SFN is indicated by one bit at a preset locationon the PBCH. Therefore, the PBCH carries eight bits of the SFN: theseven most significant bits and the least significant bit. For example,if the one bit at the preset location is 0, it indicates that the leastsignificant bit of the SFN of the radio frame in which the PBCH islocated is 0. If the one bit at the preset location is 1, it indicatesthat the least significant bit of the SFN of the radio frame in whichthe PBCH is located is 1. It can be understood that, the one bit at thepreset location may alternatively be 1, and it indicates that the leastsignificant bit of the SFN of the radio frame in which the PBCH islocated is 0, or the one bit at the preset location is 0, and itindicates that the least significant bit of the SFN of the radio framein which the PBCH is located is 1. This is not limited in thisapplication.

In another possible implementation, the indication information of theleast significant bit of the SFN is indicated by a relative locationrelationship between an SSS and a PSS in an SS block in which the PBCHis located. One SS block includes four symbols: one symbol for an SSS,one symbol for a PSS, and two symbols for PBCHs. The relative locationrelationship between the SSS and the PSS is a timing relationshipbetween the SSS and the PSS. FIG. 4A is a schematic diagram of animplementation of the indication information of the least significantbit of the SFN according to the embodiment shown in FIG. 3. As shown inFIG. 4A, the SSS is preceding the PSS. FIG. 4B is a schematic diagram ofanother implementation of the indication information of the leastsignificant bit of the SFN according to the embodiment shown in FIG. 3.As shown in FIG. 4B, the PSS is preceding the SSS. Different relativelocation relationships between the SSS and the PSS indicate differentleast significant bits of the SFN. For example, it may be defined that,when the SSS is preceding the PSS, the least significant bit of the SFNis 1, and when the PSS is preceding the SSS, the least significant bitof the SFN is 0.

In this application, that the network device determines indicationinformation of a least significant bit of the SFN indicates that thenetwork device determines both an implementation of the indicationinformation of the least significant bit of the SFN and specific contentof the indication information of the least significant bit. To bespecific, the network device determines whether the indicationinformation of the least significant bit is indicated by the one bit atthe preset location on the PBCH or indicated by the relative locationrelationship between the SSS and the PSS in the SS block in which thePBCH is located, and determines, based on the least significant bit ofthe SFN, a specific value of the one bit at the preset location or aspecific relative location relationship between the SSS and the PSS.

S302: The network device determines at least one of a scrambling code, aCRC check mask, or a redundancy version of the PBCH.

The at least one of the scrambling code, the CRC check mask, or theredundancy version is the same within one radio frame group, and isdifferent in different radio frame groups. The radio frame group are tworadio frames for which SFN mod 8=2n and SFN mod 8=2n+1 among eightconsecutive radio frames in which a radio frame for which SFN mod 8=0 isused as a start frame, where n=0, 1, 2, 3. Within one radio frame group,two remaining bits of an SFN of one radio frame are the same as tworemaining bits of an SFN of the other radio frame. The two remainingbits are a second least significant bit and a third least significantbit of the SFN.

Specifically, when sending the PBCH, the network device processes thePBCH by using the at least one of the scrambling code, the CRC checkmask, or the redundancy version of the PBCH. For example, the networkdevice uses the scrambling code to scramble the PBCH, uses the CRC checkmask to encode the CRC code of the PBCH, or performs puncturing onencoded information carried on the PBCH, which means performing ratematching to form a redundancy version. It can be understood that, thenetwork device may scramble the PBCH and encode the CRC code of thePBCH, or may scramble the PBCH, encode the CRC code of the PBCH, andperform rate matching on the encoded information carried on the PBCH. Inthis application, the network device may determine the at least one ofthe scrambling code, the CRC check mask or the redundancy version of thePBCH based on a one-to-one correspondence between the two remaining bitsof the SFN of the radio frame in which the PBCH is located and the atleast one of the scrambling code, the CRC check mask, or the redundancyversion.

In this application, a radio frame group is defined as two radio framesfor which SFN mod 8=2n and SFN mod 8=2n+1 among eight consecutive radioframes in which a radio frame for which SFN mod 8=0 is used as a startframe, where n=0, 1, 2, 3. Therefore, the eight consecutive radio framesin which the radio frame for which SFN mod 8=0 is used as the startframe may be divided into four radio frame groups: radio frames forwhich SFN mod 8=0 and SFN mod 8=1 are one group, radio frames for whichSFN mod 8=2 and SFN mod 8=3 are one group, radio frames for which SFNmod 8=4 and SFN mod 8=5 are one group, and radio frames for which mod8=6 and SFN mod 8=7 are one group. That the at least one of thescrambling code, the CRC check mask, or the redundancy version is thesame within one radio frame group means that, when just the scramblingcode is used to process the PBCH, a plurality of PBCHs sent within aradio frame group all have a same scrambling code, when just the CRCcheck mask is used to process the PBCH, a plurality of PBCHs sent withina radio frame group all have a same CRC check mask, when just theredundancy version is used to process the PBCH, a plurality of PBCHssent within a radio frame group all have a same redundancy version, whenboth the scrambling code and the CRC check mask are used to process thePBCH, a plurality of PBCHs sent within a radio frame group all have asame scrambling code and a same CRC check mask, when both the scramblingcode and the redundancy version are used to process the PBCH, aplurality of PBCHs sent within a radio frame group all have a samescrambling code and a same redundancy version, or when both the CRCcheck mask and the redundancy version are used to process the PBCH, aplurality of PBCHs sent within a radio frame group all have a same CRCcheck mask and a same redundancy version, or when the scrambling code,the CRC check mask, and the redundancy version are used to process thePBCH, a plurality of PBCHs sent within a radio frame group all have asame scrambling code, a same CRC check mask, and a same redundancyversion. There is a mapping relationship between the two remaining bitsof the SFN of the radio frame in which the PBCH is located and the atleast one of the scrambling code, the CRC check mask, and the redundancyversion. In addition, within a radio frame group, the at least one ofthe scrambling code, the CRC check mask, and the redundancy version isthe same. Therefore, within a radio frame group, two remaining bits ofan SFN of one radio frame in which a PBCH is located are the same as tworemaining bits of an SFN of the other radio frame in which a PBCH islocated. In other words, two remaining bits in a radio frame for whichSFN mod 8=2n are the same as two remaining bits in a radio frame forwhich SFN mod 8=2n+1. It should be noted that, a reason why eightconsecutive radio frames are used is that a PBCH TTI is 80 ms. It can belearned that, there is a mapping relationship between the radio framegroup, the two remaining bits of the SFN, and the at least one of thescrambling code, the CRC check mask, and the redundancy version. Forexample, two remaining bits of an SFN corresponding to the radio framegroup including the two radio frames for which SFN mod 8=0 and SFN mod8=1 are 00, two remaining bits of an SFN corresponding to the radioframe group including the two radio frames for which SFN mod 8=2 and SFNmod 8=3 are 01, two remaining bits of an SFN corresponding to the radioframe group including the two radio frames for which SFN mod 8=4 and SFNmod 8=5 are 10, and two remaining bits of an SFN corresponding to theradio frame group including the two radio frames for which SFN mod 8=6and SFN mod 8=7 are 11.

A quantity of PBCHs sent within one radio frame group is determinedbased on an SS block sending periodicity of the network device. The SSblock sending periodicity of the network device includes two types: adefault periodicity and indicated periodicities. The default periodicityis 20 ms, and the indicated periodicities include 5 ms, 10 ms, 20 ms, 40ms, 80 ms, and 160 ms. The SS block sending periodicity indicates aninterval at which PBCHs are sent within one PBCH TTI.

FIG. 5A is a schematic diagram of locations of PBCHs sent within an80-ms TTI at a sending interval of 20 ms according to an embodimentshown in FIG. 3. As shown in FIG. 5A, when the sending interval is 20ms, four PBCHs can be sent within one TTI at four locations: SFN mod8=0, SFN mod 8=2, SFN mod 8=4, and SFN mod 8=6, respectively. In thiscase, within one radio frame group, one PBCH is sent. FIG. 5B is aschematic diagram of locations of PBCHs sent within an 80-ms TTI at asending interval of 10 ms according to an embodiment shown in FIG. 3. Asshown in FIG. 5B, when the sending interval is 10 ms, eight PBCHs can besent within one TTI at eight locations: SFN mod 8=0, SFN mod 8=1, SFNmod 8=2, SFN mod 8=3, SFN mod 8=4, SFN mod 8=5, SFN mod 8=6, SFN mod8=7, respectively. FIG. 5C is a schematic diagram of locations of PBCHssent within an 80-ms TTI at a sending interval of 5 ms according to anembodiment shown in FIG. 3. As shown in FIG. 5C, when the sendinginterval is 5 ms, 16 PBCHs can be sent within one TTI. Within one radioframe group, four PBCHs can be sent.

S303: The network device processes the PBCH based on the at least one ofthe scrambling code, the CRC check mask, or the redundancy version ofthe PBCH, and sends the PBCH to a terminal device in the radio framecorresponding to the SFN.

Specifically, after determining the at least one of the scrambling code,the CRC check mask, or the redundancy version of the PBCH, the networkdevice processes the PBCH. The network device sends the PBCH in theradio frame in which the PBCH is located, that is, sends the PBCH in theradio frame corresponding to the SFN of the radio frame in which thePBCH is located. It can be understood that, the network device alsosends the at least one of the scrambling code, the CRC check mask, orthe redundancy version of the PBCH while sending the PBCH.

S304: The terminal device receives the PBCH sent by the network device.

The PBCH includes the seven most significant bits of the SFN of theradio frame in which the PBCH is located.

Specifically, the terminal device in this application may be a wirelessterminal or a wired terminal. The wireless terminal may be a deviceproviding voice and/or data connectivity to a user, or a handheld devicehaving a wireless connection function, or another processing deviceconnected to a wireless modem. The wireless terminal may communicatewith one or more core networks by using a radio access network (RadioAccess Network, RAN). The wireless terminal may be a mobile terminal,such as a mobile phone (or referred to as a “cellular” phone) and acomputer provided with a mobile terminal, for example, a portable,pocket-sized, handheld, computer built-in, or in-vehicle mobileapparatus, and exchanges voice and/or data with the radio accessnetwork. For example, the wireless terminal may be a device such as apersonal communications service (PCS) phone, a cordless telephone set, asession initiation protocol (SIP) phone, a wireless local loop (WLL)station, or a personal digital assistant (PDA). The wireless terminalmay alternatively be referred to as a system, a subscriber unit, asubscriber station, a mobile station, a mobile console (Mobile), aremote station, a remote terminal, an access terminal, a user terminal,a user agent, or a user device (User Device or User Equipment). This isnot limited herein.

After receiving the PBCH, the terminal device can determine the sevenmost significant bits, carried on the PBCH, of the SFN of the radioframe in which the PBCH is located.

S305: The terminal device determines the least significant bit of theSFN based on the indication information of the least significant bit ofthe SFN.

Specifically, when the indication information of the least significantbit of the SFN is indicated by the one bit at the preset location on thePBCH, the terminal device may determine the least significant bit of theSFN based on one bit information at the preset location on the PBCH.When the indication information of the least significant bit of the SFNis indicated by the relative location relationship between the SSS andthe PSS in the SS block in which the PBCH is located, after receivingthe PBCH, the terminal device determines the least significant bit ofthe SFN based on the relative location relationship between the SSS andthe PSS in the SS block in which the PBCH is located. In addition, theSSS may be used as a demodulation reference signal for the PBCH. In theSS block, the SSS is located between symbols of two PBCHs. In this way,the SSS is relatively close to the symbols of both PBCHs, improving PBCHdemodulation performance.

A correspondence between the one bit at the preset location on the PBCHand the least significant bit of the SFN, and a correspondence betweenthe least significant bit of the SFN and the relative locationrelationship between the SSS and the PSS may be notified to the terminaldevice by the network device in advance.

S306: The terminal device determines, based on the PBCH, the at leastone of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH, and determines the two remaining bits of the SFNbased on a one-to-one correspondence between the two remaining bits ofthe SFN and the at least one of the scrambling code, the CRC check mask,or the redundancy version of the PBCH.

Specifically, the terminal device may determine the at least one of thescrambling code, the CRC check mask, or the redundancy version of thePBCH in a PBCH decoding process. The terminal device may determine,based on the one-to-one correspondence between the two remaining bits ofthe SFN and the at least one of the scrambling code, the CRC check mask,or the redundancy version of the PBCH, the two remaining bits of the SFNof the radio frame in which the PBCH is located. The one-to-onecorrespondence between the two remaining bits of the SFN and the atleast one of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH means that, when just the scrambling code is used inthe PBCH decoding process, two remaining bits of an SFN corresponding toone scrambling code are different from two remaining bits of an SFNcorresponding to another scrambling code, when just the CRC check maskis used in the PBCH decoding process, two remaining bits of an SFNcorresponding to one CRC check mask are different from two remainingbits of an SFN corresponding to another CRC check mask, when just theredundancy version is used in the PBCH decoding process, two remainingbits of an SFN corresponding to one redundancy version are differentfrom two remaining bits of an SFN corresponding to another redundancyversion, and when both the scrambling code and the redundancy versionare used in the PBCH decoding process, two remaining bits of an SFNcorresponding to one group of scrambling code and redundancy version aredifferent from two remaining bits of an SFN corresponding another groupof scrambling code and redundancy version.

S307: The terminal device determines, based on the least significantbit, the seven most significant bits, the second least significant bit,and the third least significant bit of the SFN, the SFN of the radioframe in which the PBCH is located.

Specifically, the terminal device may determine, based on the leastsignificant bit, the seven most significant bits, the second leastsignificant bit, and the third least significant bit of the SFN, the SFNof the radio frame in which the PBCH is located.

Optionally, a scrambling code corresponding to two remaining bits of oneSFN and a scrambling code corresponding to two remaining bits of anotherSFN are different segments of one scrambling code sequence, where thetwo remaining bits of the one SFN are different from the two remainingbits of the another SFN, or a scrambling code corresponding to tworemaining bits of one SFN and a scrambling code corresponding to tworemaining bits of another SFN are different scrambling code sequences,where the two remaining bits of the one SFN are different from the tworemaining bits of the another SFN.

Optionally, a CRC check mask corresponding to two remaining bits of oneSFN and a CRC check mask corresponding to two remaining bits of anotherSFN are different mask sequences, where the two remaining bits of theone SFN are different from the two remaining bits of the another SFN.

Optionally, a redundancy version corresponding to two remaining bits ofone SFN and a redundancy version corresponding to two remaining bits ofanother SFN are different redundancy versions obtained by performingdifferent rate matching on encoded information carried on the PBCH,where the two remaining bits of the one SFN are different from the tworemaining bits of the another SFN. A rate matching process is a processfor performing puncturing on the encoded information carried on thePBCH.

It should be noted that, that two remaining bits in one SFN aredifferent from two remaining bits in another SFN means that, fordifferent SFNs, for example, two SFNs: an SFN 1 and an SFN 2, tworemaining bits of the SFN 1 are different from two remaining bits of theSFN 2, or at least one bit of two remaining bits of the SFN 1 isdifferent from at least one bit of two remaining bits of the SFN 2.

On the terminal device side, when determining the two remaining bits ofthe SFN, the terminal device only needs to perform four blind detectionsbecause only two bits need to be determined. In comparison with a mannerof directly setting eight scrambling codes to distinguish between eightSFNs within one TTI, blind detection complexity is reduced.

In a case of a PBCH sending interval of 40 ms, 80 ms, or 160 ms, thisPBCH transmission method is also applicable.

In a circumstance of poor channel quality, the terminal device maycombine a plurality of PBCHs for decoding, in order to successfullydecode the PBCH.

Optionally, based on a preset combination interval, the terminal devicemay combine PBCHs separated by the combination interval among aplurality of PBCHs. The preset combination interval may be 20 ms and/or40 ms. A possible combination manner is that, when the terminal deviceunsuccessfully decodes the PBCH by combining PBCHs separated by acombination interval of 20 ms among a plurality of PBCHs, the terminaldevice may combine PBCHs separated by a combination interval of 40 msamong a plurality of PBCHs.

Optionally, according to a combination rule indicated by the networkdevice, the terminal device may combine, in a combination mannerindicated in the combination rule, PBCHs among a plurality of PBCHs thatare within a combination interval indicated in the combination rule. Thecombination rule includes the combination manner and/or the combinationinterval.

Optionally, the terminal device may determine a first periodicity forsynchronization signal sending by the network device, determine, basedon a mapping relationship between the first periodicity forsynchronization signal sending and the combination interval, acombination interval corresponding to the first periodicity, andcombine, based on the combination interval, PBCHs separated by thecombination interval among a plurality of PBCHs. When the firstperiodicity for synchronization signal sending is 5 ms, 10 ms, or 20 ms,the combination interval is 20 ms, when the first periodicity forsynchronization signal sending is 40 ms, the combination interval is 40ms, or when the first periodicity for synchronization signal sending is80 ms or 160 ms, combination is not performed.

According to the PBCH transmission method provided in this application,the network device determines the SFN of the radio frame in which thePBCH is located, adds the seven most significant bits of the SFN to thePBCH, and determines the indication information of the least significantbit of the SFN. The network device determines the at least one of thescrambling code, the CRC check mask, or the redundancy version of thePBCH. The at least one of the scrambling code, the CRC check mask, orthe redundancy version is the same within one radio frame group, and isdifferent in different radio frame groups. The radio frame group are tworadio frames for which SFN mod 8=2n and SFN mod 8=2n+1 among eightconsecutive radio frames in which a radio frame for which SFN mod 8=0 isused as a start frame, where n=0, 1, 2, 3. Within one radio frame group,two remaining bits of an SFN of one radio frame are the same as tworemaining bits of an SFN of the other radio frame. The two remainingbits are the second least significant bit and the third leastsignificant bit of the SFN. The network device processes the PBCH basedon the at least one of the scrambling code, the CRC check mask, or theredundancy version of the PBCH, and sends the PBCH to the terminaldevice in the radio frame corresponding to the SFN. The terminal devicereceives the PBCH sent by the network device. The PBCH includes theseven most significant bits of the SFN of the radio frame in which thePBCH is located. The terminal device determines the least significantbit of the PBCH based on the indication information of the leastsignificant bit of the SFN. The terminal device determines, based on thePBCH, the at least one of the scrambling code, the CRC check mask, orthe redundancy version of the PBCH, and determines the two remainingbits of the SFN based on the one-to-one correspondence between the tworemaining bits of the SFN and the at least one of the scrambling code,the CRC check mask, or the redundancy version of the PBCH. The terminaldevice determines, based on the least significant bit, the seven mostsignificant bits, the second least significant bit, and the third leastsignificant bit, the SFN of the radio frame in which the PBCH islocated. This implements that, in a 5G system, the terminal device candetermine the two remaining bits of the SFN by just performing blinddetection on at least one of the following: four scrambling codes, fourCRC check masks, or four redundancy versions. In comparison with animplementation of directly setting eight scrambling codes to determinean SFN of a radio frame in which a PBCH is located, a quantity of blinddetections is reduced from 8 to 4, thereby reducing blind detectioncomplexity. In addition, the PBCH transmission method can be applicableto scenarios with different quantities of PBCHs sent within one PBCHTTI. To be specific, the foregoing implementation can be applicable toscenarios in which one PBCH, two PBCHs, four PBCHs, eight PBCHs, or 16PBCHs can be sent within one TTI. An application scope is relativelywide.

FIG. 6 is a schematic structural diagram of Embodiment 1 of a terminaldevice according to this application. As shown in FIG. 6, the terminaldevice provided in this application includes the following modules.

A receiving module 61 is configured to receive a PBCH sent by a networkdevice.

The PBCH includes seven most significant bits of an SFN of a radio framein which the PBCH is located.

A determining module 62 is configured to determine a least significantbit of the SFN based on indication information of the least significantbit of the SFN.

The determining module 62 is further configured to determine, based onthe PBCH, at least one of a scrambling code, a CRC check mask, or aredundancy version of the PBCH, and determine two remaining bits of theSFN based on a one-to-one correspondence between the two remaining bitsof the SFN and the at least one of the scrambling code, the CRC checkmask, or the redundancy version of the PBCH.

The two remaining bits are a second least significant bit and a thirdleast significant bit of the SFN.

The determining module 62 is further configured to determine, based onthe least significant bit, the seven most significant bits, the secondleast significant bit, and the third least significant bit of the SFN,the SFN of the radio frame in which the PBCH is located.

Optionally, the indication information of the least significant bit ofthe SFN is indicated by one bit at a preset location on the PBCH.

Optionally, the indication information of the least significant bit ofthe SFN is indicated by a relative location relationship between aprimary synchronization signal and a secondary synchronization signal ina synchronization signal block in which the PBCH is located.

A scrambling code corresponding to two remaining bits of one SFN and ascrambling code corresponding to two remaining bits of another SFN aredifferent segments of one scrambling code sequence, where the tworemaining bits of the one SFN are different from the two remaining bitsof the another SFN, or a scrambling code corresponding to two remainingbits of one SFN and a scrambling code corresponding to two remainingbits of another SFN are different scrambling code sequences, where thetwo remaining bits of the one SFN are different from the two remainingbits of the another SFN.

A CRC check mask corresponding to two remaining bits of one SFN and aCRC check mask corresponding to two remaining bits of another SFN aredifferent mask sequences, where the two remaining bits of the one SFNare different from the two remaining bits of the another SFN.

A redundancy version corresponding to two remaining bits of one SFN anda redundancy version corresponding to two remaining bits of another SFNare different redundancy versions obtained by performing different ratematching on encoded information carried on the PBCH, where the tworemaining bits of the one SFN are different from the two remaining bitsof the another SFN.

The terminal device provided in this application is specificallyconfigured to execute the method executed by the terminal device in theembodiment shown in FIG. 3, with a similar implementation process, asimilar technical principle, and a similar technical effect. Details arenot described herein again.

FIG. 7 is a schematic structural diagram of Embodiment 2 of a terminaldevice according to this application. As shown in FIG. 7, the terminaldevice provided in this application includes a transceiver 71, a memory72, configured to store an instruction, and a processor 73, connected toboth the memory 72 and the transceiver 71, and configured to execute theinstruction, so as to execute the following steps when executing theinstruction, including receiving a PBCH sent by a network device, wherethe PBCH includes seven most significant bits of an SFN of a radio framein which the PBCH is located, determining a least significant bit of theSFN based on indication information of the least significant bit of theSFN, determining, based on the PBCH, at least one of a scrambling code,a CRC check mask, or a redundancy version of the PBCH, and determiningtwo remaining bits of the SFN based on a one-to-one correspondencebetween the two remaining bits of the SFN and the at least one of thescrambling code, the CRC check mask, or the redundancy version of thePBCH, where the two remaining bits are a second least significant bitand a third least significant bit of the SFN, and determining, based onthe least significant bit, the seven most significant bits, the secondleast significant bit, and the third least significant bit of the SFN,the SFN of the radio frame in which the PBCH is located.

The terminal device provided in this application is specificallyconfigured to execute the method executed by the terminal device in theembodiment shown in FIG. 3, with a similar implementation process, asimilar technical principle, and a similar technical effect. Details arenot described herein again.

FIG. 8 is a schematic structural diagram of Embodiment 1 of a networkdevice according to this application. As shown in FIG. 8, the networkdevice provided in this application includes the following modules.

A determining module 81 is configured to: determine an SFN of a radioframe in which a PBCH is located, add seven most significant bits of theSFN to the PBCH, and determine indication information of a leastsignificant bit of the SFN.

The determining module 81 is further configured to determine at leastone of a scrambling code, a CRC check mask, or a redundancy version ofthe PBCH.

The at least one of the scrambling code, the CRC check mask, or theredundancy version is the same within one radio frame group, and isdifferent in different radio frame groups. The radio frame group are tworadio frames for which SFN mod 8=2n and SFN mod 8=2n+1 among eightconsecutive radio frames in which a radio frame for which SFN mod 8=0 isused as a start frame, where n=0, 1, 2, 3. Within one radio frame group,two remaining bits of an SFN of one radio frame are the same as tworemaining bits of an SFN of the other radio frame. The two remainingbits are a second least significant bit and a third least significantbit of the SFN.

The sending module 82 is configured to: process the PBCH based on the atleast one of the scrambling code, the CRC check mask, or the redundancyversion of the PBCH, and send the PBCH to a terminal device in the radioframe corresponding to the SFN.

Optionally, the indication information of the least significant bit ofthe SFN is indicated by one bit at a preset location on the PBCH.

Optionally, the indication information of the least significant bit ofthe SFN is indicated by a relative location relationship between aprimary synchronization signal and a secondary synchronization signal ina synchronization signal block in which the PBCH is located.

A scrambling code corresponding to two remaining bits of one SFN and ascrambling code corresponding to two remaining bits of another SFN aredifferent segments of one scrambling code sequence, where the tworemaining bits of the one SFN are different from the two remaining bitsof the another SFN, or a scrambling code corresponding to two remainingbits of one SFN and a scrambling code corresponding to two remainingbits of another SFN are different scrambling code sequences, where thetwo remaining bits of the one SFN are different from the two remainingbits of the another SFN.

A CRC check mask corresponding to two remaining bits of one SFN and aCRC check mask corresponding to two remaining bits of another SFN aredifferent mask sequences, where the two remaining bits of the one SFNare different from the two remaining bits of the another SFN.

A redundancy version corresponding to two remaining bits of one SFN anda redundancy version corresponding to two remaining bits of another SFNare different redundancy versions obtained by performing different ratematching on encoded information carried on the PBCH, where the tworemaining bits of the one SFN are different from the two remaining bitsof the another SFN.

The network device provided in this application is specificallyconfigured to execute the method executed by the network device in theembodiment shown in FIG. 3, with a similar implementation process, asimilar technical principle, and a similar technical effect. Details arenot described herein again.

FIG. 9 is a schematic structural diagram of Embodiment 2 of a networkdevice according to this application. As shown in FIG. 9, the networkdevice provided in this application includes: a transceiver 91, a memory92, configured to store an instruction, and a processor 93, connected toboth the memory 92 and the transceiver 91, and configured to execute theinstruction, so as to execute the following steps when executing theinstruction: determining an SFN of a radio frame in which a PBCH islocated, adding seven most significant bits of the SFN to the PBCH, anddetermining indication information of a least significant bit of theSFN, determining at least one of a scrambling code, a CRC check mask, ora redundancy version of the PBCH, where the at least one of thescrambling code, the CRC check mask, or the redundancy version is thesame within one radio frame group, and is different in different radioframe groups, and the radio frame group are two radio frames for whichSFN mod 8=2n and SFN mod 8=2n+1 among eight consecutive radio frames inwhich a radio frame for which SFN mod 8=0 is used as a start frame,where n=0, 1, 2, 3, within one radio frame group, two remaining bits ofan SFN of one radio frame are the same as two remaining bits of an SFNof the other radio frame, and the two remaining bits are a second leastsignificant bit and a third least significant bit of the SFN, andprocessing the PBCH based on the at least one of the scrambling code,the CRC check mask, or the redundancy version of the PBCH, and sendingthe PBCH to a terminal device in the radio frame corresponding to theSFN.

The network device provided in this application is specificallyconfigured to execute the method executed by the network device in theembodiment shown in FIG. 3, with a similar implementation process, asimilar technical principle, and a similar technical effect. Details arenot described herein again.

This application further provides a communications system. Thecommunications system includes the terminal device in the embodimentshown in FIG. 6 or FIG. 7, and the network device in the embodimentshown in FIG. 8 or FIG. 9.

This application further provides a readable storage medium thatcontains an executable instruction. When at least one processor of theterminal device executes the executable instruction, the terminal deviceis configured to execute the method executed by the terminal device inthe embodiment shown in FIG. 3.

This application further provides a readable storage medium thatcontains an executable instruction. When at least one processor of thenetwork device executes the executable instruction, the network deviceis configured to execute the method executed by the network device inthe embodiment shown in FIG. 3.

This application further provides a program product. The program productincludes an executable instruction, and the executable instruction isstored in a computer readable storage medium. At least one processor ofa terminal device may read the computer executable instruction from thereadable storage medium, and the at least one processor executes theexecutable instruction, so that the terminal device implements themethod executed by the terminal device in the embodiment shown in FIG.3.

This application further provides a program product. The program productincludes an executable instruction, and the executable instruction isstored in a computer readable storage medium. At least one processor ofa network device may read the computer executable instruction from areadable storage medium, and the at least one processor executes theexecutable instruction, so that the network device implements the methodexecuted by the network device in the embodiment shown in FIG. 3.

Persons of ordinary skill in the art may understand that all or some ofthe steps of the method embodiments may be implemented by a programinstructing relevant hardware. The program may be stored in a computerreadable storage medium. When the program runs, the steps of the methodembodiments are performed. The foregoing storage medium includes anymedium that can store program code, such as a read only memory (ROM), arandom access memory (RAM), a magnetic disk, or an optical disc.

1-25. (canceled)
 26. A scrambling method, comprising: scrambling aphysical broadcast channel (PBCH) according to a first scrambling codeof the PBCH, wherein the first scrambling code is one of four scramblingcodes, wherein a combination of a second least significant bit and athird least significant bit of a system frame number (SFN) associatedwith a radio frame of the PBCH indicates one value of four values, andwherein the four scrambling codes have a one-to-one correspondence withthe four values; and sending the PBCH to a terminal device.
 27. Themethod according to claim 26, wherein the PBCH is sent in the radioframe with the SFN, and wherein the one value of four values indicatedby the combination of the second least significant bit and the thirdleast significant bit of the SFN corresponds to the first scramblingcode.
 28. The method according to claim 26, wherein the four scramblingcodes are different segments of one scrambling code sequence.
 29. Themethod according to claim 26, wherein the four scrambling codes are fourdifferent scrambling sequences.
 30. An apparatus, comprising: atransceiver; a processor; and a non-transitory computer-readable storagemedium storing a program to be executed by the processor, the programincluding instructions to: to scramble a physical broadcast channel(PBCH) based on a first scrambling code of the PBCH, wherein the firstscrambling code is one of four scrambling codes, wherein a combinationof a second least significant bit and a third least significant bit of asystem frame number (SFN) associated with a radio frame of the PBCHindicates one value of four values, and wherein the four scramblingcodes have a one-to-one correspondence with the four values; and causethe transceiver to send the PBCH to a first terminal device.
 31. Theapparatus according to claim 30, wherein the PBCH is sent in the radioframe with the SFN, and wherein the one value of four values indicatedby the combination of the second least significant bit and the thirdleast significant bit of the SFN corresponds to the first scramblingcode.
 32. The apparatus according to claim 30, wherein the fourscrambling codes are different segments of one scrambling code sequence.33. The apparatus according to claim 30, wherein the four scramblingcodes are four different scrambling sequences.
 34. The apparatusaccording to claim 30, wherein the apparatus is a second terminaldevice.
 35. A non-transitory computer readable medium, comprisingcomputer program instructions which when executed by one or moreprocessors cause the one or more processors to: scramble a physicalbroadcast channel (PBCH) based on a first scrambling code of the PBCH,wherein the first scrambling code is one of four scrambling codes,wherein a combination of a second least significant bit and a thirdleast significant bit of a system frame number (SFN) associated with aradio frame of the PBCH indicates one value of four values, and whereinthe four scrambling codes have a one-to-one correspondence with the fourvalues; and send the PBCH to a terminal device.
 36. The non-transitorycomputer readable medium according to claim 35, wherein the PBCH is sentin the radio frame with the SFN, and wherein the one value of fourvalues indicated by the combination of the second least significant bitand the third least significant bit of the SFN corresponds to the firstscrambling code.
 37. The non-transitory computer readable mediumaccording to claim 35, wherein the four scrambling codes are differentsegments of one scrambling code sequence.
 38. The non-transitorycomputer readable medium according to claim 35, wherein the fourscrambling codes are four different scrambling sequences.
 39. Anapparatus, comprising: a memory; and one or more processors, wherein theone or more processors are configured to: scramble a physical broadcastchannel (PBCH) based on a first scrambling code of the PBCH, wherein thefirst scrambling code is one of four scrambling codes, wherein acombination of a second least significant bit and a third leastsignificant bit of a system frame number (SFN) associated with a radioframe of the PBCH indicates one value of four values, and wherein thefour scrambling codes have a one-to-one correspondence with the fourvalues; and send the PBCH to a terminal device.
 40. The apparatusaccording to claim 39, wherein the PBCH is sent in the radio frame withthe SFN, and wherein the one value of four values indicated by thecombination of the second least significant bit and the third leastsignificant bit of the SFN corresponds to the first scrambling code. 41.The apparatus according to claim 39, wherein the four scrambling codesare different segments of one scrambling code sequence.
 42. Theapparatus according to claim 39, wherein the four scrambling codes arefour different scrambling sequences.
 43. The method according to claim26, wherein the seven most significant bits of the SFN are sent with thePBCH.
 44. The apparatus according to claim 30, wherein the seven mostsignificant bits of the SFN are sent with the PBCH.
 45. Thenon-transitory computer readable medium according to claim 35, whereinthe seven most significant bits of the SFN are sent with the PBCH.